From 06fbefe5f6c864294e945b8f7190ab643852f4aa Mon Sep 17 00:00:00 2001
From: Marcel van Lohuizen <mpvl@gmail.com>
Date: Thu, 9 Feb 2023 20:16:27 +0100
Subject: [PATCH] internal/core/adt: detect closed lists as fatal errors
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Tightening of error handling. This may eliminate some
disjunctions earlier, causing better error handling.

Issue #2244

Signed-off-by: Marcel van Lohuizen <mpvl@gmail.com>
Change-Id: I0b059969b2b272c903ed4e4eea368822da93d822
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/549658
Unity-Result: CUEcueckoo <cueckoo@cuelang.org>
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
---
 cue/testdata/references/index.txtar  | 12 ++++++------
 cue/testdata/resolve/016_index.txtar | 12 ++++++------
 internal/core/adt/context.go         |  3 +++
 3 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/cue/testdata/references/index.txtar b/cue/testdata/references/index.txtar
index 81fb2a48b29..cf958da77b0 100644
--- a/cue/testdata/references/index.txtar
+++ b/cue/testdata/references/index.txtar
@@ -30,15 +30,15 @@ varNegativeIndex: {
 	a: [1, 2, 3][n]
 }
 -- out/eval/stats --
-Leaks:  15
+Leaks:  12
 Freed:  36
 Reused: 33
-Allocs: 18
-Retain: 15
+Allocs: 15
+Retain: 12
 
-Unifications: 43
-Conjuncts:    56
-Disjuncts:    48
+Unifications: 40
+Conjuncts:    50
+Disjuncts:    45
 -- out/eval --
 Errors:
 outOfBoundsDisjunction: invalid list index 1 (out of bounds):
diff --git a/cue/testdata/resolve/016_index.txtar b/cue/testdata/resolve/016_index.txtar
index be564bcd2ff..bec1271c944 100644
--- a/cue/testdata/resolve/016_index.txtar
+++ b/cue/testdata/resolve/016_index.txtar
@@ -92,15 +92,15 @@ e7: def["b"]
   e7: 〈0;def〉["b"]
 }
 -- out/eval/stats --
-Leaks:  16
+Leaks:  10
 Freed:  32
 Reused: 26
-Allocs: 22
-Retain: 23
+Allocs: 16
+Retain: 16
 
-Unifications: 40
-Conjuncts:    61
-Disjuncts:    53
+Unifications: 34
+Conjuncts:    48
+Disjuncts:    46
 -- out/eval --
 Errors:
 c: invalid list index "3" (type string):
diff --git a/internal/core/adt/context.go b/internal/core/adt/context.go
index b8aefafbdd7..b15d56c096e 100644
--- a/internal/core/adt/context.go
+++ b/internal/core/adt/context.go
@@ -876,6 +876,9 @@ func (c *OpContext) lookup(x *Vertex, pos token.Pos, l Feature, state VertexStat
 		// inability to look up a field as "final", as it may resolve down the
 		// line.
 		permanent := x.status > Conjuncts
+		if m, _ := x.BaseValue.(*ListMarker); m != nil && !m.IsOpen {
+			permanent = true
+		}
 		if (state > Partial || permanent) && !x.Accept(c, l) {
 			code = 0
 		} else if hasCycle {